Remove WorkIdentity Instead of assigning arbitrary ids to all work items that are part of the execution graph, include the `Nodes` in `ExecuteTaskBuildOperationDetails` and `ExecuteScheduledTransformationStepBuildOperationDetails` so they can be queries for dependency successors directly. This eliminates the need to query `TaskExecutionGraphInternal` or `ExecutionPlan` for the node in order to determine its dependencies.